Modulating control device



June 9K, -1942. vR. v. DERRAH 2,285,913

MODULATING CONTROL DEVICE* Filed Jan. 17, 1940 3 Sheets-Sheet l :inventor Ctforneg me 9? @ERRAH 2,285,913

MGDULHLING CONTROL DEVICE Filed Jan. 17, 1940 5 Sheets-Sheet 2 JQ? nl di?. wm

WWW/WWW Patented June 9, 1942v UNITED STATE s PATENT OFFICE 2,285,913 MonUna'rrNo ooN'raoL nnvrcn,

Robert V. Denali, Beverly Hills, Calif. Application January 17, 1940, serial Nu.,314,291 .4 claims. (ci. 23a-cs) My present invention relates to electrical control apparatus and has for an object the provision of apparatus which, while not so limited, is particularly suitable for modulating or positioning control means for a condition changing device in accordance with the magnitude of the required change in said condition. Said condition may be, for example, one of temperature, humidity or pressure.

Another object of my invention is theprovision of electrical switching means for periodically completing a circuit, the portion of "the period `during which the circuit is complete being variable.

Another cbject is the provision of means for periodically electrically energizing a condition changing control device, the portion of the period during which the device is energized being normally proportional to the difference between the desired and the then existing condition.

Another object is the provision of means for alternately moving an operating member in opposite directions, the movement of the member being so retarded inboth directions that eifective positioning of the member results.

Other objects and advantages. of-'myinventioJ will be oundin Vthefdelsciiption, the drawings,

v...and the appended claims.

For complete understanding of the invention, reference may be had to the following detailed description and accompanying drawings, where- Figure l is a sectional view of an operating device embodying a feature o my invention;

Figure 2 is a sectional view oi.' a thermostatic kcontrol device embodying my invention;

ble sealed vessel or bellows I8 containing a volatile fluid. Mounted on the top of said vessel, is a similar vessel I9, held in position by an adjusting screw 20 threaded in the top Wall of the housing. Interposed between the two vessels is the top plate 2I of -a yoke 'member 22. Projections 23 andl 24, and 25, formed respectively on the plates 2I and il, cooperate with depressions formed in the end walls of the vvessels 4and serve to prevent lateral movement of the vessels and the yoke Iwith respect to each other and to the housing. The upper end of the valve stem I5 is threaded in the bottom plate 26 of the yoke 22. A spring 21, compressed between the plates Il and 28,. urges the yoke downward and the valve membertowardclosed position. Mounted v.surrounding `a lower portion of vessel I8 is an bimetallic member 33, insulatingly and adjustably mounted on a wall of the case, carries on its upper end a contact element 34 cooperable with the arm 32. Surrounding a portion of member 3 I, and electrically insulated therefrom, is a heat- Figure 5 is a side elevation, vwith its cover partly broken away, of a modiiied form of thermostatic control device embodying my invention;

` Figure 6 is an enlarged sectional view of the device shown in Fig. 5;

Each of Figures 7 and 8 is a diagrammatic view of the devices shown in Figs. 1 and 2; and

Each of Figures 9 and 10 is a diagrammatic view of the devices shown in Figs. 4, 5 and 6.

Referring rst to Figs. 1, 2 and 3 of the drawings, the numeral II indicates a valve casing having a partition provided with a iluid control port I2. Closing an opening in the upper portion vof said valve casing is a threaded plate I3 having v member 3 I.

ing coil 35 connected at its upper end to a terminal 38 and at its lowexend to an insulated adjustable contact screw 31 cooperable with a contact element 38 carried by the bimetallic This member 3I is connected througha switch 38 to terminal 40. Terminals 36 and 40 are also connected to a source of current (nt shown) by wires 4|. 1t will thus be seen that, when switch 39 is closed, current can ilow through the heating coil 35, contacts 3l and 38, and bimetallic member 3I. 'Ihis constitutes a conventional flasher system in which the heating of the member 3l functions to periodically move the member 3| in a clock-wise direction to open its heating coil circuit. In this periodic movement of member 3|, the contact arm 32 is brought into and out-of engagement with the contact 34 carried by the helical bimetallic member 33 and connected to terminal 42. This results in the closing and opening of the circuit through the heating coil 28 of the valve shown in Fig. 1, one of the lead wires 29 for the coil 28 being connected at terminal 36 directly to one of the supply wires 4|, and the other of wires 29 being connected through terminal 42, contact 34, contact arm 32, member 3|, switch 39 and terminal 40 to the other of the supply wires 4|.i

The operation of the system shown in Figs. 1-3 may better be understood by reference to the equivalent diagrammatic showing of Figs. v'1 and 8. In these gures the numeral 50 indicates a Valve member cooperable with a port to control fluid flow through a valve casing 52.

tween the upper portion of which and a plate 55 fixed to a housing 55, is anexpansible-contractcontractible vessel 59 is held in engagement with the upper surface of the yoke by a screw 80 threaded in the upper wall o! the housing. yA heating coil 6| for the vesselA 51 is connected by a wire 62 to a source of current (not shown) 'and by a Wire 63 to a helical bimetallic member 64 carrying a contact element 65 cooperable with a ilexible contact arm 66 secured tothe lower end of a bimetallic member 61, the upper end of which is connected through a switch 68 to a wire 69 which is also connected to said source of current. l

Surrounding a portion of member 61 is a heating coil 10, the upper end of which is connected to the source of current by a wire 1|, and the lower end to a fixed contact element 12 cooperable with another contact element 13 secured to the lower end of member 61. This constitutes a conventional ilasher system for periodically `movingthe member 61.

In Fig.l 7, the contacts 65 and 66 are shown in engagement and the valve operator heating coil 6| is therefore energized, with the result that the i vessel 51 is expanded to move the yoke and the valve, member-upwardggainst the bias of spring 58 and unheated vessel 59. n Fig. 8, the member 51 is shown Warped to its maximum extent, this member moving through a substantial arc after theseparation of contacts 12 and 13 on account of the thermal lag of the system. With.

contacts 65 and 66 thus now open, heating coi] 6| is unenergized and the-valve tends to close. However, cooling of the vessel 51 is relatively slow and before the valve member is able to move downward through an appreciable distance, the member 61 will have cooled suiciently to per- .mit contacts 55 and 61 to again engage.- 'I'he flasher system may be so arranged and adjusted that the member61 completes its cycle in from 5 to 60 seconds, dependent on the degree of control desired. Y

When, by variation of temperature in the space wherein the thermostat' is located, contact element 65, carried by the bimetallic member 54, moves farther into the path of travel of the con- 1 tact element carried by contact arm 56, as shown contact arm 68 and therefore no energization of 76 A stem 53 connects the valve membertogayo'ke 54y be heating coil 6| occurs. Although both of the members 64 and 6,6 have herein been shown and described'as exible, it is obvious that, for enicient operation of the system. it suffices that but 5 one of these members be ilexible.

It will thus be seen that the duration of energization of the heating coil 6| is dependent on the position of the contact element 65 in the path of travel of the contact carried by arm 66.`

Normally, the duration of energization is proportional to the diier'ence between the existing'temperature at the thermostat and the desired tem- .lperature for which the bimetallic member 84 has ybeen set.

1 5 Assuming, for example, that the valve controls the supply of fuel to a heating system for the iwspace'wherein the thermostat is located, when Y'the -temperature in vthespace is low, the contactA carried by the bimtallic member Gf Wil,1.be in such position that it is continuously in engagement Awith the contact arm 66 throughoutthe c'ycle of movement of member 51. Consequently the heating coil 5| will 'be continuously energized with the result that the valve will assume a fullopen position. When the temperature in the space now rises, say, to just below the temperature for which thethermostat is set, the member 6 4 will assume, for example, the position shown at 14 in Fig. 8, the heating coil 6| being energized during a major portion of the cycle so that the valve member will remain in an elevated position.

If the temperature in the space continues to rise,

say', to just above the temperature for which the thermostat is set, and the member 64 assumes A the position shown in Fig. 7, the heating coil will be energized only during a small portion of the cycle and the valve member will assume a lower A position, possibly uctuating slightly upward and downward of that position if the rate of movement' of member 61 is relatively slow. If, on 4further rise of temperature in the space, v the member 64 assumes the position shown at 15 in Fig. 8, no energization of the heating coil will v occur and the valve will therefore close.

In the prior art, systems have been disclosed wherein the positioning of a control device is accomplished by variation in the amount of a coni tinuous flow of energizing current, as by a temperature controlled rheostat. By my present invention I accomplish the desired result by varying the duration of flow of current ofgawwxed value by periodical interruption so that the average energy imparted to the operating device is proportional to the position of the controlling mem-ber. X

The function of the vsselolgof Fig. 1 (or 59 in Figs. '1 and 8) is to compensatforeh nges in the ambient temperature adjacent the valve operator. Equal and opposed forces are thermally produced in bothof the vessels |8 and V| 9 and consequently change in ambient temperature does not tend to move the operator.

Referring now to Figs. 4-6 of the drawings wherein is disclosed a modified control system embodying my present invention, the numeral 88 indicates an apertured operator housing, to theV inner wall of which is secured a hollow coil member. 8| electrically connected by wires 82 to 4a thermostatie control device shown in Fig, 5. Ar-

same is energized is the magnetic cylindrical upper end portion 83 of a yoke member 84. nThe v ranged to be attracted into'said coil when the said bottom yend plate and a bracket 88 secured to the side wall of the housing, urges said yoke and stem downward. Secured respectively to the upper Wall of housing 80 and to bracket 88 are opposed cup members 89 and 90, cooperable respectively with plungers or piston members 9| and 92. These plungers are carried by hollow rods 93 and 94, respectively, each threaded in the bore of the cylindrical upper portion 83 of yoke 84. These hollow rods permit fluid communication between the interior of the cup members 89 and 90, ilowbeing restricted by an apertured disk 95, which may be replaced with a similar disk having an aperture of a different size'if it is desired to vary the rate of fluid ilow between the cup members.

In Figs. 5 and 6, each of which shows the same control device, the numeral indicates a vented case wherein is mounted an electromagnetic operator essentially identical with that shown in Fig. 4. As this operator was fully described in the preceding paragraph, further description would be merely repetitions and is therefore deemed unnecessary.

Secured to the lower end of stem |0| of the operator is a collar |02, of insulating material, to which is fixed a flexible contact arm |03 carrying a contact element |04. Surrounding an upper portion of the stem |0|, and slidable thereon, is an insulating collar in the outer wall of which is recessed a metal contact ring |06. Cooperable with said ring are contact ngers |01, and |08,

insulatingly supported by a bracket |09 mounted on a wall of the housing. Longitudinal movement of collar |05 with respect to the stem is limited by an enlarged lower portion ||0 of stem coil 8| is deenergized. the operator is moved slowly downward by the force of spring 81, fluid now passing in the opposite direction between the cups.

The operation of the modiiled system shown in Figs. 4-6 may more readily be explained by reference tothe equivalent diagrammatic showing of Figs. 9 and 10. Fundamentally, the operation is the same as that of the system disclosed in the other figures (Figs. 7 and 8) of the drawings. The operators and the control devices of the two systems are interchangeable; for example, the device shown in Fig. 2 may be employed to control the operator of Fig. 4, or the device of Figs. 5 and 6 to control the operator of Fig. 1.

In Figs. 9 and 10, a yoke |30 carries on its lowerend an operating stem |3| and on its upper end a magnetic plunger |32 cooperable with a coil |33. The yoke is downwardly biased by a spring |34 and is retarded in its upward and downward movement by iluidly intercommunicating dashpots |35 and |36. To theoperating 19| and by a central boss formed on ,the bottom plate of yoke I|2. The collar |05 is normally held stationary and floating on the stem by the force exerted on opposite sides of the collar by the lingers |01 and |08.

Insulatingly and adjustably mounted on a wall of the housing is a helical bimetallic member 3 carrying on its free end a contact element H4 cooperable with the contact element |84. Insulated terminals H5 and ||6 are provided for the connection to the device, by wires ||1 and H8, of a source of current (not shown). The

lupper lead of the operator coil is connected directly to the upper power terminal I|5 andthe lower lead to contact nger |01. The opposed contact finger |08 is connected through a switch |20 to the lower power terminal IIB. It will be seen that when ring '|06 is in such position as to interconnect the contact fingers |01 and |08, current can flow through the operator coil.

` Also connected to the lower p'ower terminal H6 through yswitch |20 is the contact arm |03. The inner end of bimetallic member ||3 being connected to terminal ||9, it will be seen that when contacts |04 and ||4 are in engagement current can -flow to coil 8|, one lead of that coil being connected to the terminal ||9 and the other lead directly to the upper power terminal ||5.

`When the coil 8| of the electromagnetic device shown in Figs, 4-6 is energized, the plunger 83 is attracted by the coil. However, its resultant upward movement is retarded by plungers 9| and 92 which, respectively, increase and decrease the fluid pressure in the cups 89 and 90, the fluid passing slowly from the one to the other through the restricted opening in disk 95. The iluid may normally beI air, or, if slower movement is desired, it may be a. liquid such as o il. When the stem |31 of an electromagnetic device |38, substantially identical with that just described, is insulatingly secured a flexible contact arm |39. Cooperable with said contact arm is a contact element |40 carried by a bimetallic member |4|. An insulating collar |42 having a bore freely tting stem |31 is provided with a recessed contactring |43 with which a pair of contact fingers |44 and |45 are cooperable. These fingers normally hold the collar' stationary, so that the stem |31 can slide therein. As shown in Fig. 9, the contact lingers are in engagement with the opposite sides of the ring |43 so that the lower end of coil -|48 is now connected to the source of power through the interconnected fingers |44 and |45 and wire |41. The upper end of coil |46 beingdirectly connected to the power, the stem |31 is slowly moved upward, the collar remaining stationary until its lower end is engaged by the enlarged portion |48 of stem |31, when the ring is moved out of contact with the fingers, as shown in Fig. 10. The coil |46 now being deenergized, the stem |31 moves `slowly downward under the force of spring |49, the' collar again being held stationary until its upper end is engaged by the bottom portion of yoke |50, when the ring is again moved into contact with the fingers, as shown in Fig. 9, to initiate repetition f the cycle. It will be seen that the apparatus just described constitutes means for periodically moving the contact arm |39 in a manner similar to that of the flasher device shown in Figs. 2, 7 and 8.

Whenthe arm |39 is brought into engagement with the contact element |40 it'will be seen that the power circuit to coil |33 is completed. As was described in connection with Figs. '1 and 8, the duration of the engagement of contact arm |39 withv contact element |40, and consequently the duration of energization of coil |33, is dependent on the respective position of contact element |40 in the path of travel of the contact arm, and the operator stem I3 iscorrespondingly positioned. v

vThe systemof my present invention may also be adapted to the control of an operator employthe contacts effecting movement of the motor in one direction, and Aengagement with thel other eiiecting movement oi the motor in the opposite ing substantial volume and containing an expansible-contractible iiuid, said heat motor also including. an electric heater` for supplying heat to said last-named fluid; and means determining the ratio of the periods of energization and deenergization of said heater, comprising a pair 'of relatively movable cooperating electrical contacts, means for cyclically varying the position of one of said contacts, means for urging the other contact towardy said one of said contacts comprising means responsive to variations in a a 'circuit' for energizing said heater directly controlled by said contacts.

3. In a system for adjusting the position of a member controlling the now or fluid: a heat motor operatively connected to said member and including an expansible-contractible bellows having substantial volume and containing an expansible-contractible iiuid, said heat motor also including an electric heater for supplying heat to said bellows and thereby to the fluid contained therein, said bellows, fluid and heater being so arranged that movement of said member due t0 energization or deenergization of said heater is relatively sluggish; and means determining the ratio o f the periods of energization and deenergization of said heater, comprising a pair of relatively movable cooperating Aelectrical contacts,

. of said contacts, and'a circuit for energizing said controlling condition for creating a force which' varies in accordance withthe departure of the degree of said condition from that desired, and a circuit for energizing said heater directly controlled by said contacts.

2. In a system for adjusting the position of a member controlling the flow of `fluid: a heat motor operatively connected to said member and including. a main expansible-contractible bellows having substantial volume and containing an expansible-contractible fluid, said heat motor also including an electric heater for supplying heat to said last-named uid, said heat motor also havmeans for cyclically varying the position of one of said contacts, means operating in accordance with temperature variations for applying a force in accordance with said temperature variations for urging the other contact toward the said one heater directly controlled by said contacts.

4. In a system for adjusting the position of. a member controlling the iiow of iiuid: a heat motor operatively connected to said member and including a main expansible-contractible bellows having substantial volume and containing an expansible-contractible fluid, said heat motor also including an electric heater for supplying heat to said last-named iiuid, said heatmotor also having a compensating expansible-contractible bellows operating in reverse to said main bellows andsubjected only to circumambient temperature; and means determining the ratio o! the periods of energization and deenergization of said heater and thereby the position of said member,

' fcomprising a pair of relatively movable coopering a compensating expansible-contractible bellows operating in reverse to said main bellows `and subjected only to circumambient temperature;v and means determining the ratio of the periods of energization and deenergization of said heater, comprising a pair of relatively movable cooperating electrical contacts, means for cyclically varying the position of one of said contacts, means operating in accordance with temperature variations f or applying a force in accordance with said temperature variations for urging the other contact toward the said one of said contacts, and

ating electrical contacts, means energized by the source provided for the 'energization of said heater for continuously moving one of said contactsv in a xed path, ambient temperature responsive means for moving the other of'said contacts into -said path so that it is engaged by the said one contact element in its movement, at least one of said contact-moving means being yieldable so that the duration of engagement of said contacts is dependent on the relative position of said second contact in the path, and a circuit for energizing said heater controlled by said contacts.

ROBERT v. DERRAH. 

